Normal framing of a multi-story building, such as a house or commercial building involves framing floors with joists which span the area to create a flooring structure. Floor boards are then placed over the joists. As each level of the building is added this flooring structure is repeated.
Moreover, during the construction process, there are several steps which require the use of scaffolding for the exterior of the building. For example, once all the studding of walls is completed, scaffolding is required to install the exterior sheathing. This involves the cutting and securing of plywood to the exterior side of the wall studs. Other steps to reach a finished building which occasion the need for scaffolding are house-wrap, siding/brick work, windows, gutters, eve covers, trim, painting, . . . etc. Many of the these steps cannot be performed while working on a ladder which is leaned against the building, particularly for buildings having more than two stories.
Therefore, the contractor must erect scaffolding for the various tradesmen to stand on while working with both hands free. Scaffolding comes in three basic types. The first and most common is “free-standing”. This is a structure which must be assembled like an erector set, with a plurality of legs and walking surfaces, and is not physically attached to the house structure. It is very time consuming to erect and costly if rented. Another structure is called a “pump-jack” scaffold. This typically involves single columns that are temporarily attached to the exterior of the house for support, with the bottom of the column resting on the ground. After a few of these are set up, walking surfaces are laid on an arm that extends from the columns. A foot on these arms is then pumped make the support arms climb the column. Motorized manlifts, also known as “cherry pickers”, are another type of scaffolding system. These also are very costly to own or rent, and may not fit in all areas around a building. In fact, if the building is being constructed where one of the exterior walls is on a steep hillside, “free-standing” and “cherry-picker” scaffolding will not work at all. It is also very dangerous to setup “pump-jacks” on a steep hill.